Known from US 2008/0078455 A1 is a system to automatically shut down valves in an emergency situation, specifically to open or close line valves for oil or gas on a drilling platform. Here, spring force initiates a switching movement of a slide valve in a pipeline, requiring a considerable amount of energy for executing the switching process.
Known to the applicant is to pneumatically activate closing mechanisms of the preforms and finished forms of an IS machine, for example, by means of valve assemblies, which all are mounted on a valve block, which in turn is connected with a machine frame, with an adapter plate interspersed. Each valve assembly associated with an individual movement section of the machine, e.g., one for closing and opening a specific preform, is referred to as a track. Each of the valve assemblies consists of a cartridge carrier that holds two switching cartridges, each of which can be actuated by means of an optionally electrically or manually activatable pilot control valve. The pilot control valves set up to actuate switching valves formed by the switching cartridges control the movement of the respective form halves, wherein, if operating air is supplied separately via the adapter plate, safety valves are formed between the latter and an air distributor or, in the absence of a separate supply of operating air, by some other external valve. An interruption of control air for each track of the I.S. machine, i.e., one such interruption control confined to a single valve assembly, is here not provided, wherein furnishing additional tracks with mutually independent safety valves is associated with more space being required for their accommodation, and in many instances is very difficult if not impossible to realize due to space limitations.
A comparable problem exists in conjunction with controlling the other mechanisms of the valve assemblies allocated to the IS machine and also mounted on the valve block.
In light of the stricter legal requirements to be expected in the future as relates to work safety, it has become necessary to equip a larger number of valve assemblies with a safety valve, a requirement that is frequently virtually impossible to satisfy with conventional technology, in particular for space considerations.
However, a cascade consisting of an electrical signal that actuates the pilot control valve, which in turn actuates the switching valve and reaches the respective closing mechanism via an external safety valve, is undesirable from a control technology standpoint.